Polymerization of cyclic esters



United States Patent 3,021,317 POLYMERIZATION OFCYCLIC ESTERS Eugene F. Cox and'Fritz Hostettler, Charleston, W. Va., assignors to Union Carbide Corporation, a corporation of New York No Drawing. Filed Dec. 3, 1959, Ser. No. 856,913 23 Claims. (Cl. 260-783) This invention relates to a process for polymerizing cyclic esters and to the products resulting therefrom.

The most generally familiar works on the polymerization .of lactones are the now classical investigations of W. H. Carothers. For instance, Oarothers was able to polymerize delta-valerolactone to poly-delta-valerolactone by heating at 8085 C. for a period of about 13 days, or by contacting delta-valerolactone with potassium carbonate catalyst at a temperature of 80-85 C. for a period of about days. The resulting polymers were soft waxes possessing average molecular weights of approximately 2000 which had relative low thermal stabilities. The literature reports that attempts to polymerize gamma-butyrolactone have been unsuccessful, and the corresponding polyester is not known. In 1934, there was reported the preparation of poly-epsilon-caprolactone by heating epsilon-caprolactone at about 150 C. for a period of 12 hours, or by contacting epsilon-caprolactone with potassium carbonate at about 150 C. for a period of 5 hours. The resulting epsilon-caprolactone polymers had melting points of about 53 -55 C. and average molecular weights of about 4000. The polymers were hard, brittle Waxes which could not be colddrawn into fibers. transformation of glycolide under the influence of heat or a trace of zinc chloride into a polymeric solid melting at 220 C. On being distilled in a vacuum it was reconverted to the monomer melting at 8687 'C. The literature also reports the polymerization of lactide at elevated temperatures to a resinous mass. ,A similar effect is also obtained at relatively lower temperatures by employing potassium carbonate as the catalyst.

In a broad aspect the present invention is directed to the process for polymerizing monomeric cyclic esters in contact with a group IA metal catalyst, i.e., lithium, sodium, potassium, rubidium, and cesium, to produce useful polyester products, both the cyclic ester reagents and the catalysts being describedhereinafter in a more appropriate section. The average molecular weights of the resulting polymers can range from about several hundred to about several thousand. 'The homopolymers, copolymers, and'terpolymers prepared by the practice of the instant invention are highly useful products as will become apparent at a later section herein. 'In addition, the polymerization reaction can oftentimes be conducted at lower temperatures and 'at faster polymerization rates heretofore unattainable in lactone polymerization art.

Accordingly, one or more of the following objects will be achieved by the practice of this invention.

It is an object of this invention to provide a novel process for homopolymerizing monomeric cyclic esters to produce useful homopolymers. It is another object of this invention to provide a novel process for polymerizing an admixture containing at least two different monomeric cyclic esters to produce useful polymers. A further object of this invention is to prepare lactone polymers having a high degree of'utility and application in the cosmetic, wax, polish, molding, coating, etc, fields.

Collected Papers of Wallace H. Carothers, edited by H. Mark and G. S. Whitby, volume I, Interseience Publishers,

Bischofi and Waldon describe the 2 .Other objects will become apparent to those skilled-in the art in the light of the instant specification.

In one embodiment the monomeric cychc esters employed in the polymerization process of this invention can be characterized by the following formula:

1 0 ll (3-0 (Ro-R)x (R-C-R),

wherein each R, individually, can be hydrogen, alkyl,

aryl, alkaryl, aralkyl, cycloalkyl, halo, haloalkyl, alkoxyalkyl, alkoxy, aryloxy, and therlike; wherein A can valent saturated aliphatic hydrocarbon group, and the like; wherein x is an integer from -1 to 15 inclusive; wherein z is an integer having a value of zero or one; with the provisos that (a) the sum of x+y+z cannot equal 3, (b) the total number of atoms forming the cyclic ester ring does not exceed 18, preferably does not exceed 9, (c) the total number of organic substituents (such as those described for the R'variables) attached to the carbon atoms contained in the cyclic ester ring does not exceed 4, preferably does not exceed 3, (d) from 2 to 4 continuously linked carbon atoms contained in the cyclic ester ring can represent a portion of a saturated cycloaliphatic hydrocarbon nucleus which contains from 4 to 10 ring carbon atoms, and (e) the four R variables attached to any two adjacent carbon atoms contained in the cyclic ester ring can represent a portion of a fused aromatic hydrocarbon nucleus.

With reference to Formula, I supra, illustrative R radicals include, among others, methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, t-butyl, amyl, the hexyls, the heptyls, the octyls, dodecyl, octadecyl, phenyl, benzyl, tolyl, xylyl, ethylphenyl, butylphenyl, phenethyl, phenylpropyl, phenylbutyl, cyclopentyl, 2-propylcyclohexyl, cyclohexyl, Z-methylcyclohexyl, cycloheptyl, chloromethyl, chloroethyl, bromopropyl, bromobutyl, chloro, fluoro, bromo, iodo, methoxymethyl, ethoxyethyl, propoxymethyl, butoxypropyl, methoxy, ethoxy, n-propoxy, .n-butoxy, isopentoxy, n-hexoxy, 2-ethylhe'xo xy, 3-methyloctoxy, decoxy, dodecoxy, octadecoxy, phenoxy, ethylphenoxy, propylphenoxy, dimethylphenoxy, phenylpropoxy, and the like. It is preferred that each .R, individually, be hydrogen, alkyl, and/or alkoxy, and preferably still, that each R, individually, be hydrogen, lower alkyl, e.g., methyl, ethyl, n-propyl, isobutyl, and/or lower alkoxy, e.g., methoxy, ethoxy, propoxy, n-butoxy, and the like. It is further preferred that thetotal number "of carbon atoms in the substituents attached to the cyclic ester ring does not exceed twelve. Cycloalkyl and lower alkyl-snbstituted cycloalkyl radicals which have from 5 to 7 carbon atoms in the cycloaliph'atic nucleus also are preferred.

In the discussion of the generic class of monomeric cyclic esters (Formula 'I) contemplated in the process of the invention, five provisos enumerated from (a) through '(e) have been setforth. Proviso -(a) states that the sum of x+y+z cannot be a number equal to three. This proviso excludes cyclic ester compounds which contain five atomsin the ring such as, for example,

W. H. Carothers, .G. L. Dorough, and F. I. van'Natta, Jonr. Amer. Chem. Soc.', 54,'761(1932).

, zene, naphthalene and the like.

and the substituted gamma-butyrolactones have been unsuccessful. Attempts to polymerize the cyclic esters, e.g., gamma-butyrolactones, beta-oxa-gamma-butyrolactones,

V and the like, in the process of this invention likewise have has been observed that when the total number of organic I substituents on the cyclic ester ring approached four or more, then the polymerizability of the cyclic ester monomer in the process of the invention diminished drastically. Proviso (d) states that from 2 to 4 continuously linked'carbon atoms contained in the cyclic ester ring can represent a portion of a saturated cycloaliphatic hydrocarbon nucleus which contains from 4 to 10 ring carbon atoms such as, for example, a saturated cycloaliphatic hydrocarbon nucleus derived from cycloalkane, alkyl-substituted cycloalkane, cyclobutane, cyclopentane, cyclohexane, cycloheptane, cyclooctane, methylcyclopentane, methylcyclohexane, and the like. Thus, for example, the following illustrative cyclic esters would be included in this proviso:

2-oxabicyelo[3.2.2]nonan-3-one Proviso (2) states that the four R variables attached to any two adjacent carbon atoms contained in the cyclic ester ring can represent a portion of a fused aromatic hydrocarbon nucleus, that is, an aromatic nucleus derived from benzene, alkylbenzene, methylbenzene, propylben- To illustrate this proviso, the following compoundis depicted structurally.

2,3,4,5-tetrahydro-2-keto-benzoxepln atoms designated by the numerals 7, 8, 9, and 10. The following compound further illustrates proviso (e).

2-(2-hydroxymethylphenyl)benzene carboxylic acid lactone Representative monomeric cyclic esters which can be employed as starting materials in the method of the invention include, for example, beta-propiolactone, deltavalerolactone, epsilon-caprolactone, 7-hydroxyheptanoic acid lactone, 8-hydroxyoctanoic acid lactone, l2-hydroxydodecanoic acid lactone, 13-hydroxytridecanoic acid lactone, l4-hydroxytetradecanoic acid 1actone,15-hydroxypentadecanoic acid lactone, 16-hydroxyhexadecanoic acid lactone, l7-hydroxyheptadecanoic acid lactone; the alpha, alpha dialkyl beta propiolactone, e.g., alpha, alpha-dimethyl-beta-propiolactone, alpha, alpha-diethylbeta-propiolactone, alpha, alpha-dipropyl-beta-propiolactone, and the like; the monoalkyl-delta-valerolactones, e.g., the monomethylmonoethyl-, monoisopropyl-, monobutyl-, monohexyl-, monodecyl-, and monododecyldelta-valerolactones and the like; the dialkyl-delta-valerolactones in which the two alkyl groups are substituted on the same or different carbon atoms in the cyclic ester ring, e.g., the dimethyl-, diethyl-, disopropyb, dipentyl-, and di-n-octyl-delta-valero-lactones, and the like; the the monoalkyl-, dialkyl-, or trialkyl'epsilon-caprolactones, e.g., the monomethyl-, monoethyl-, monoisopropyl monohexyl-, mono-n-octyl-, dimethyl-, diethyl-, di-npropyI-, diisobutyl-, di-n-hexyl, tn'methyl, triethyl, and trin-propyl-epsilon-caprolactones, and the like; the monoalkoxyand dialkoxy-delta-valerolactones and epsiloncaprolactones, e.g., monomethoxy-, monoethoxy-, monoisopropoxy-, dimethoxy-, diethoxy-, and dibutoxy-deltavalerolactones and epsilon-caprolactones, and the like. Further illustrative cyclic esters include 3-ethyl-2-keto- 1,4 dioxane, gamma(1 isopropyl-4-methylcyclohexyl)= epsilon caprolactone, 3 bromo 2,3,4,5-tetrahydrobenzoxepin-Z-one, 2-(2'-hydroxyphenyl)benzene carboxylic acid lactone, 10-hydroxyundecanoic acid lactone, 2,5,6,7- tetrahydrobenzoxepin-Z-one, 9-oxabicyclo[5.2.2]undecan- 8-one, 4-oxa-l4-hydroxytetradecanoic acid lactone, alpha, alpha bis(chloromethyl) propiol'actone, 1,4-dioxane-2- one, 3-n-propyl-2-keto-l,4-dioxane, 3-(2-ethylhexyl)-2- keto-l,4-dioxane, and the like. Illustrative subclasses of cyclic esters which are eminently suitable in the process of the instant invention include the unsubstituted lactones and the oxalactones which contain from six to eight atoms in the lactone ring, preferably delta-valerolactone, epsilon-caprolactone, the keto-dioxanes, and the like; the monoand polyalkyl-substituted lactones and loxalactones which contain from six to eight atoms in the lactone ring, preferably the monoand poly-lower 'alkyl-detla-valerolactones, epsilon-caprolactones, and their corresponding oxalactones wherein the alkyl substituen-t(s) contains from 1 to 4 carbon atoms, and the like; and the monoand polyalkoxy-substituted lactones and oxalactones which contain from six to eight atoms in the lactone n'ng, preferably the mono. and poly-lower alkoxy-delta-valero lactone, epsilon-caprolactones, and their corresponding oxalactones wherein the alkoxy substituent(s) contains from 1 to 4 carbon atoms.

The unsubstituted and substituted delta-valerolactones, epsilon-caprolactones, zeta-enantholactones, and higher membered lactones, e.g., monoand polyalkyl-substituted delta-valerolactones, monoand polyalkoxy-substituted delta-valerolactones, monoandpolycycloalkyl-substituted delta-valerolactones, aryl-substituted delta-valerolactones, monoand polyhaloalkyl-substituted delta-valerolactones, monoand polyalkyl-substituted epsilon-caprolactones, monoand polyalkoxy-epsilon-caprolactones, aryl-substituted epsilon-caprolactones, monoand polyhaloalkylsubstituted epsilon-caprolactones, monoand polyalkylsubstituted zeta-enantholactones, and various other lactones described previously can be prepared by reacting the corresponding cyclic ketone with an anhydrous solutioncomprising peraceticacid and acetone. It is desirable to add the peracetic acid solution to an excess of ketone, e.g., 5 to 1 molar ratio of ketone to peracetic acid, in a still kettle maintained under reflux. The pressure canbe adjusted so as to provide a kettle, temperature of, for example, about 70 C. Acetone, acetic acid lay-product, and minor amounts of ketone can be con tinuously removed throughout the addition period. Subsequently, the lactone product can'be recovered from the still kettle by conventional techniques such as by distillation.

Stoll and Rouve report the preparation of lactones which contain up to 22 carbon atoms in the lactone nucleus by a process which comprises contacting the corresponding terminal hydroxy saturated aliphatic monocarboxylic acid with benzenesulfonic acid catalyst in boiling benzene. These authors also report the preparation of other lactones such as 14-alkyl-14-hydroxytetradecanoic acid lactone, e.g., l4-hydroxypentadecanoic acid lactone, and oxa-l5-hydroxypentadecanoic acid lactone, e.g., l2-oxa-lS-hydroxypentadecanoic acid lactone. Palornaa and Tonkola 6 teach the preparation of 3-oxa-6 hydroxyhexanoic acid lactone byheating the corresponding terminal hydroxy saturated aliphatic monocarboxylic acid. The preparation of 2-keto-1,4-dioxane, 3-alkyl-2-keto-1,4 dioxane, polyalkoxy substituted delta-valerolactone, monoand polyalkyl-substituted delta-valerolactone, alkoxyalkyl-substituted delta-valerolactone, etc., is recorded by Carothers et al." The preparation of dialkylesubstituted, dihalo-substituted lactone, e.g., gamma, delta-dibromo-gamma, delta-dimethyl delta-valerolactone is reported in the literature by Levina et a1. German Pat. No. 562,827 discloses the preparation of 2,3,4,5-tetrahydrobenzoxepin-Z-one Whereas the literaturereports the position isomer, namely, 2,5,6,7-tetrahydrobenzoxepin-2- one. Cycloalkyl-substituted epsilon-caprolactone, e.g., gamma(l isopropyl -.4 methylcy'clohexyllepsiloncaprolactone is disclosed by Belov and Kheifitsl Mc- Kay et al. have recorded the preparation of halo-substituted, haloalkyl-substituted delta-valerolactone. The literature also reportsthe preparation of various other cyclic esters.

The group IA metal catalysts are employed incatalytically significant quantities. In general, a catalyst concentration in the range of from about.0.00l, and lower, to about 10, and higher, weight percent, based on the Weight of total monomeric feed, is suitable. A catalyst concentration in the range of from about 0.01 to about 3.0" weight percent is preferred. A catalyst concentration in the range of from about 0.05 to about 1.0. weight percent is -highly preferred. For optimum results, the particular catalyst employed, the nature of the monomeric reagent(s), the operative conditions under which the poly'merizationreaction is conducted, and other factors will largely determine the desired catalyst concentration.

The polymerization reaction can be conducted over a wide temperature range. Depending upon various factorssuch as the nature of the monomeric reagent(s) employed, the particular catalyst employed, the concentration of the catalyst, and thelike, the reaction tempera- 11 J. Amer. Chem. Soc.. 77, 5601-6 (1955).

ture can be as low as 40 C., and lower, and as high as 250" C., and higher. A suitable temperature range is from about 20 to about 225 C. A reaction tempera ture in the range of from about 0 C. to about 200 Cl is preferred.

The polymerization reaction preferably occurs in the liquid phase, and to this extent suificientpressure is employed to maintain an essentially liquid reaction mixture regardless whether or not an inert normally-liquid organic vehicle is employed. Preferably, the polymerization reaction is conducted under an inert atmosphere, e.g., nitrogen, butane, helium, etc. The ultimate molecular weight of the resulting polymer will depend, to an extent, upon various factors such as the temperature, the choice and concentration of the catalyst, the use and amount, of an inert normally-liquid organic vehicle(s), and the like.

In general, the reaction time will vary depending on the operative temperature, the nature of the monomeric cyclic esters employed, the particular catalyst and the concentration employed, the use of an inert normallyliquid organic vehicle, and other factors. The reaction time can vary from several seconds to several hours, or more, depending on the variables illustrated above.

It is preferred to conduct the polymerization reaction in the essential absence of impurities which contain active hydrogen since the presence of such impurities tends to deactivate the catalyst and/or increase the induction pe:- riod. The minimization or essential avoidance of impurities such as Water, carbon dioxide, aldehydes, ketones, etc., is highly desirable. It is also preferred that the polymerization reaction be conducted under substantially anhydrous conditions.

When polymerizating an admixture containing at least two difierent cyclic esters, the proportions of said cyclic esters can vary over the entire range. Broadly the concentration of each monomeric cyclic ester is in therauge of from about 3 to about 97 weight percent, based on the total weight of said cyclic esters. The preferred rangeis from about 15 to about weight percent. Admixtures containing epsilon-caprolactone and monoand/or polyalkyl-substituted:epsilon-caprolactone (including isomeric mixtures thereof) are highly preferred as starting materials in the process of the invention. Admixturescontaining different monoand/or polyalkyl-substituted epsilon-caprolactones (including isomeric mixtures of the same and/ or different monoand/or polyalkyl-substituted epsilon-caprolactones) also are highly preferred.

The polymers of this invention can be prepared via the bulk polymerization, suspension polymerization, or the solution polymerization routes. The. polymerization reaction can be carried out in the presence of an inert normally-liquid organic vehicle such as, for example, aromatic hydrocarbons, e.g., benzene, toluene, xylene, ethylbenzene, and the like; various oxygenated organic compounds such as anisole, the dimethyl and diethyl ethers of ethylene glycol, of propylene glycol, of diethylene glycol, and the like; normally-liquid saturated hydrocarbons including the open chain, cyclic, and alkyl-substituted cyclic saturated hydrocarbons such as hexane, heptane, various normally-liquid petroleum hydrocarbon fractions, cyclohexane, the alkylcyclohexanes, decahydronaphthalene, and the like. If desired, a mixture of mutually miscible inert normally-liquid organic vehicles can be employed.

The process of the invention can be executed in a batch, semi-continuous, or continuous fashion. The reaction vessel can be a glass vessel, steel autoclave, elongated metallic tube, or other equipment and material employed in the polymer art. The order of addition of catalyst and monomeric reagent(s) does not appear -to be critical. A suitable procedure is to add the catalyst to the reaction zone containing the monomeric reagent(s) and inert organic vehicle,.if any. It is highly preferred that the catalyst be added as asuspensionor dispersion in an anert normally-liquid organic vehicle such as, for instance, the inert normally-liquid saturated aliphatic and cycloaliphatic hydrocarbons, e.g., hexane, heptane, octane, cyclohexane, alkylcyclohexane, decahydronaphthalene, and the like. Incremental addition of catalyst to the reaction zone can be employed. If desired, the above procedure can be reversed, that is, the monomeric reagent(s) per se or as a solution or suspension in an inert organic vehicle can be added to the reaction zone which preferably contains the catalyst as a suspension or dispersion in an inert normally-liquid organic vehicle. Also, the catalyst, reagent(s), and inert organic vehicle, if any, can be added to the reaction zone simultaneously. The reaction zone (be it a closed vessel or an elongated tube) can be fitted with an external heat exchanger to thus control undue temperature fluctuations, or to prevent any possible run-away reaction temperatures due to the. exothermic'nature of the reaction. In a continuous operation employing as the reaction zone an elongated tube or conduit, the use of one or a plurality of'separate heat exchangers can be conveniently used. In a batch operation, stirring means can be provided for agitating the reaction mixture, as desired.

Unreacted monomeric reagent oftentimes can be recovered from the reaction product by conventional techniques such as by heating said reaction product under reduced pressure. Removal of unreacted monomeric reagent(s) and/or inert organic vehicle can be accomplished by mechanical means such as treatment of the reaction product in a Marshall Mill and the like. The

polymer product also can be recovered from the reac-' tion product by washing said reaction product with an inert normally-liquid organic vehicle, e.g., heptane, and subsequently drying same under reduced pressure at slightly elevated temperatures. Another route involves dissolution in a first inert organic vehicle, followed by the addition of a second inert organic vehicle which is miscible with the first vehicle but which is a non-solvent for the polymer product, thus precipitating the polymer product. 'If desired, the reaction product can be dissolved in an inert organic vehicle such as acetone, and the like, followed by the addition of suflicient water to the resulting solution, said Water being miscible with said inert organic vehicle but being a non-solvent for the water-insoluble polymer thereby precipitating the polymer product. Recovery of the precipitated polymer can be effected by filtration, decantation, etc., followed by drying same as indicated previously.

The linear polyester products resulting from the process of the invention can be characterized by the following recurring structural unit:

wherein the variables R, A, x, y, and 2, have the same values as shown in Formula I supra. Of course, the five provisos enumerated as (a) through (e) set forth in the discussion of Formula I supra likewise apply to the structural unit designated as Formula II above. In addition, as intimated previously, the molecular weights -of the polyester products can range from about several ganic vehicle, and the like.

It is readily aparent that the linear homopolymers are essentially characterized by the same recurring unit which falls within the scope of Formula II supra. The copolymers, terpolymers, etc., on the other hand, can contain as little as 1.0 weight percent, and lower, and upwards to 99 weight percent, and higher, of the same recurring unit. Desirable polymers are those in which the weight percent of the different recurring units is in the range of from about 3 to about 97. In the highly preferred copolymers the weight percent of the two different recurring units is in the range of from about 15 to about 85.

The polymers obtained by the process of the invention are a useful class of polyester compounds. These polymers can range from viscous liquids to very tough solids. The polymers in the range of from very viscous liquids to relatively low molecular weight, wax-like solids are useful in the preparation of cosmetics, polishes, and waxes, and as thickening agents for various lubricants. The polymers can be employed to size cellulosic material or they can be used as anti-static agents in the treatment of fibrous materials. They can also be employed as protective coatings and/or impregnants. The solid polymers are useful for the production of various shaped articles such as brush handles, buttons, lamp bases, toys, and the like. The solid polymers also are useful in the preparation of films by such techniques as milling on a two-roll mill, calendering, solvent casting, and the like.

In passing, it should be noted that one apparent advantage afforded by the practice of the invention is the preparation of copolymers, terpolymers, etc., Whose physical characteristics can be tailor-made to fit desired fields of applications and uses. In other words, by adjusting the concentration of the monomeric charge to a particular polymerization system, copolymers, terpolymers, etc., which cover a wide spectrum of properties and characteristics can be prepared, e.g., soft, rubbery polymers to very tough polymers.

In the illustrative operative examples to follow, the polymeric product oftentimes is described as possessing a certain reduced viscosity value. By this term, i.e., reduced viscosity, is meant a value obtained by dividing the specific viscosity by the concentration of the polymer in the solution, the concentration being measured in grams of polymer per 100 milliliters of solvent at a given temperature. The specific viscosity is obtained by dividing the difference between the viscosity of the solution and the viscosity of the solvent by the viscosity of the solvent. The reduced viscosity value is an indication of the molecular weight of the polymer. Unless otherwise indicated, the reduced viscosity value was determined at 30 C.

Also, in the illustrative operative examples below, the polymerization reaction was generally conducted under an inert atmosphere, e.g., nitrogen. The reaction vessel and contents, i.e., cyclic ester(s), catalyst, and inert organic vehicle, if any, were maintained, usually under agitation, in a constant temperature, e.g., 90 C., or the reaction vessel containing the cyclic ester(s) was maintained, usually under agitation, in a constant temperature and subsequently the catalyst was added thereto. Since the polymerization reaction, in general, was exothermic a rise in temperature was observed, e.g., to C. In several instances the period recorded was the time ob- .served in which the rotation of the mechanical stirrer ceased due to the high viscosity of the contents in the reaction vessel. In most cases the reaction vessel was left in the constant temperature bath for an additional period of time, e.g., about 20 minutes or longer. Unless otherwise indicated, the examination or description of the polymericproduct was conducted at room temperature, i.e., about 23 C. In general, the conversion of monomer to polymer was substantially quantitative.

9 EXAMPLE 1 (A) To a reaction vessel maintained under a nitrogen give an admixture containing 0.4 weight percent sodium,

based on the weight of said epsilon-caprolactone. The reaction vessel then was placed in a constant temperature bath maintained at 90 C. for a period of 65 hours.- Thereafter, the polymeric product was recovered. There was obtained a white, soft, solid homopolymer;

(B) In an analogous manner as above, when beta, gamma-dimethoxy-delta-valerolactone is substituted for epsilon-caprolactone and contacted with 1.0 weight percent potassium, there is obtained a solid polymer.

EXAMPLE 2 (A) To a reaction vessel maintained under a nitrogen atmosphere and which contained epsilon-caprolactone, there was charged potassium metal in an amount so as to give an admixture containing 0.5 weight percent potassium, based on the weight of said epsilon-caprolactone. The reaction vessel then was placed in a constant temperature bath maintained at 90 C. for a period of 12 hours. Thereafter, the polymeric product was recovered. Therewasohtained a solid homopoly mer which had a reduced viscosity value of 0.40 (measured at 0.2 gram of polymer in 100 ml. of chloroform at 30 C.).

(B) In an analogous manner as above, when rubidium metal is employed as the catalyst in an amount so as to give an admixture which contains 1.0 weight percent lithium, based on the weight of epsilon-caprolactone, essentially the same results are obtained.

EXAMPLE 3 (A) To a reaction vessel maintained under a nitrogen atmosphere and which contained epsilon-caprolactone, there was charged lithium metal in an amount so as to give an admixture containing 0.5. weightpercent lithium,

(B) In an analogous manner as above, when gammal-isopropy1-4-methy1cyclohexyl) -epsilon-caprolactone is substituted for epsilon-caprolactone and contacted-with 1.0 weight percent rubidium, there is obtained a viscous liquid .product.

EXAMPLE 4 (A) To areaction vessel maintained under a nitrogen atmosphere and which contained epsilon-caprolactone, there was chargedsodium (dispersed in toluene) in-an amount so as to give an admixture containingOfiweight percentsodium, based on the Weight of said epsilon-caprolactone. The reaction vessel then was placed in a constant temperature bath maintained at 90 C. Within-2 minutes the mechanical stirrer ceased due to the high viscosity of the contents in the reaction vessel. Thereafter, the polymeric. productwas recoveredfrom-the reaction vessel. There was obtained a tough, white homopolymer which had a reduced vicosity value of 1.76 (measured at.0.2 gram of polymerin 100 ml. of chloroform at-30 C.).

(B) ln-an analogous manner asabove, when gammamethyl-delta-isopropyl-epsilon-caprolactone is substituted for epsilon-caprolactone and contacted with 1.0 weight percent lithium, there is obtained a viscous liquid product.

EXAMPLE 5 To a reaction vessel maintained under a nitrogen atmos- .40- based on the weight of said epsilon-caprolactone. The.

, beta:methyldelta-valerolactone.

phere and which contained beta-methyl-delta-valerolactone, there-wascharged-sodium (dispensed-intolueneyin an amount so as to give an. admixture containing 0.5 weight percent sodium, based on the total Weightof said The reaction vessel then was placed in aconstant temperaturebath maintained at C. Within 3 minutes the mechanical stirrer ceased clue to the high viscosity of the contents in the reaction vessel. Thereafter, the polymeric product was recovered. There was obained a solid homopolymer-Whichhad a reduced'viscosity value of 0:87 (measured-at 0.2 gramoi polymer, in ml. of chloroform at 30 C.).

EXAMPLE 6 (A) To a reactionvessel maintained under a nitrogen atmosphere and which contains an isomeric mixture composed of a major proportion by weight of gamma-octylepsilon-caprolactone and a minor proportion by: weight of. epsilon-octyl-epsilon-caprolactone, there is charged sodium (dispersed in petroleum ether), in anamount so as to give an admixture containing 0.5 weight percent sodium, based on the total weight of'octyl-epsilon-capro lactone. The reaction vessel then is placed in a constant temperature bath maintained at 90 C. for a periodof 30 minutes. There is obtained a soft, solidproduct.

(B) In an analogous manner as above, when 2,3,4,5- tetrahydrobenzoxepin-Z-one is substituted for the isomeric mixture ofoctyl-epsilon-caprolactones and contacted with 1.0 weight percent potassium (dispersed in heptane), there is obtained a soft, solid polymer.

EXAMPLE 7 (A) To a reaction vessel maintained under a nitrogen atmosphere and Which'contains delta-valerolactone, there is charged sodium (dispersedin toluene) in an amount so as to give an admixture containing 0.6 weight percent sodium, based on the weight of said delta-valerolactone. The reaction vessel then is placed in a constant temperaturebath maintained'at 90 C; for a period'of two hours. Thereafter, the polymeric product is recovered. There is obtained a solid homopolymer.

(B) In an aualogous-manner as above, when3-ethyl- 2-keto-1,4-d ioxane' is substituted for delta-valerolactone and contacted with 1.0 weight percent lithium (dispersed in cyclohexane), a very viscous liquid is obtained.

EXAMPLE 8 (A) To a reaction vessel maintained'under a nitrogen atmosphere and which contains beta-methyl-delta-valerolactone (redistilled, boiling point 137 C. at 1.5 mm. of Hg; n of 1.4480) there is charged a quantity of potassium (dispersed in heptane) in an amount so as to give an. admixture containing 0.8 weight percent potassium, based on the weight of said beta-methyl-delta-valerolactone. The reaction vessel then is placed in a constant temperature bath which is maintained at C. for a period ,of-about 2 hours. Thereafter, the-polymericproduct is. recovered. There is obtained: a viscous liquid product.

(B) In an analogousmanner asabove, when 3'-oxa- 6.-hydroxyhexanoic acid lactoneis substituted for betamethyl-delta-valerolactone and contacted-with 0.5 weight percent sodium (dispersed in toluene), essentially similar results are obtained.

EXAMPLES 9-11 In; Examples 9 through 11, various copolymersare prepared ,by polymerizing an, admixture of-two lactonesin the .presence of sodium (dispersed in toluene). The .procedureemployed is similar to that-set;forth immediately preceding the operative examples. The pertinentv data and-results are recordedin Table 1 below.

Table I Example Laetone Charge 1 Catalyst Temp., Time, Description of Number Concen- 0. Min. Copolymer tration I V 9 7O epsilon-caprolactone/BO beta- 0. 6 100 12 Hard solid.

methyl-delta-valerolactone. 10 80 epsiln-caprolactone/20 beta- 0. 6 100 12 Tough solid methyl-delta-valcrolactone. 11 85 epsilon-caprolactone/l beta- 0. 6 100 Waxy solid.

methyl-delta-valerolactone.

1 Parts by weight. 1 Weight percent catalyst, based on total weight of lactone charge.

EXAMPLE 12 (A) To a reaction vessel maintained under a nitrogen atmosphere and which contains zeta-enantholactone, there is charged lithium metal in an amount so as to give an admixture containing 1.0 weight percent lithium, based on the Weight of said zeta-enantholactone. The reaction vessel'then is placed in a constant temperature bath maintained at 90 C. for a period of 40 minutes. Thereafter, the polymeric product is recovered. There is obtained a solid homopolymer.

(B) In an analogous manner as above, when l0-hy droxynndecanoic acid lactone is substituted for zeta-enantholactone and contacted With 1.0 weight percent sodium (dispersed in heptane), essentially similar results are obtained.

EXAMPLES 13-14 In Examples 13 and 14 the procedure employed is similar to that set forth immediately preceding the operative examples. The pertinent data and results are recorded in Table II below.

erative examples. The pertinent data and results are recorded in Table III below.

Table III Ratio of Epsilon-Capro- Tim Description Example Number lactone to Delta- Min. of Copolymer Valerolactone 1 20:80 20 Hard solid. 80:20 15 Tough solid.

1 Ratio is in parts by weight.

EXAMPLE 18 (A) To a reaction vessel maintained under a nitrogen atmosphere and which contains a mixture of parts by weight of cpsilon-caprolactone and 50 parts by weight of mixed octyl-epsilon-caprolactones, there is charged sodium (dispersed in cyclohexane) in an amount so as to give an admixture containing 0.4 weight percent sodium, based on the total weight of the lactone feed. The mixed Table II Example Catalyst Temp., Time, Description Number Lactone Charge 1 Catalyst Conccn- 0. Min. oi Polyester tration 13 30lzeta-enantholactone/70 epsilon-capro- Na 1. 0 110 10 Hard solid.

a one. 14 20 zeta-enanthalactone/SO cpsilon-capro- Na 1. 0 110 8 Tough solid.

lactone.

1 Admixture of two lactones is expressed as parts by weight.

1 Weight percent catalyst based N orE.Zeta/en antholactone re on total weight of lactone charge.

EXAMPLE 15 (A) To a reaction vessel maintained under a nitrogen atmosphere and which contains 2-keto-1,4-dioxane, there is charged sodium (dispersed in toluene) in an amount so as to give an admixture containing 1.0 weight percent sodium, based on the weight of said 2-keto-1,4-dioxane.

The reaction vessel then is placed in a constant temperature bath maintained at 90 C. for a period of about 10 minutes. Thereafter, the polymeric product is recovered. There is obtained a solid polymer.

(B) In an analogous manner as above, when gamma- 1-isopropyl-4-methylcyclohexyl) epsilon-caprolactone is substituted for 2-keto-1,4-dioxane and contacted with 1.0 weight percent potassium metal, there is obtained a viscous liquid product.

EXAMPLES 16-17 distilled; B.P. 72 C. at 4 mm. of Hg; no 0! 1.4689.

octyl-caprolactones comprises a major proportion by weight of gamma-octyland a minor proportion by weight of epsilon-octyl-epsilon-caprolactones. The reaction vessel then is placed in a constant temperature bath maintained at C. for a period of one hour. Thereafter, the reaction product is dissolved in acetone and reprecipitated in water. There is obtained a solid copolymer.

(B) In an analogous manner as above, when equal parts by weight of 9-oxabicyclo[5.2.2]undecan-S-one and 1,4-dioxane-2-one are employed as the monomeric feed and contacted with 1.0 weight percent potassium (dispersed in heptane), essentially similar results are obtained.

EXAMPLE 19 (A) To a reaction vessel maintained under a nitrogen atmosphere and which contains ortho-(2- hydroxyethyl)- phenylacetic acid lactone, there is charged sodium (dispersed intoluene) in an amount so as to give an admixture containing ].0 weight percent sodium, based on the Weight of said ortho-(Z-hydroxyethyl)-phenylacetic acid lactone. The reaction vessel then is placed in a constant temperature bath maintained at 90 C. for a .period of one hour. 7 There is obtained a solid polymer.

(B) In an analogous manner as above, when cis-3-oxabicyclo[5.4.01undecan-4-one is substituted for ortho-(2- hydroxyethyl)phenylacetic acid lactone and contacted with 1.0 weight percent potassium, substantially similar results are obtained.

Although the invention has been illustrated by the preceding examples, the invention is not to be construed as limited to the materials employed in the above exemplary examples, but rather, the invention encompasses the generic area as hereinabove disclosed. Various modifications and embodiments of this invention can be made without departing from the spirit and scope thereof.

What is claimed is:

l. A process which comprises contacting as the sole polymerizable reagent at least one cyclic ester characterized by the following formula:

wherein each R, individually, is selected from the group consisting of hydrogen, alkyl, aryl, alkaryl, aralkyl, cycloalkyl, halo, haloalkyl, alkoxyalkyl, alkoxy, and aryloxy; wherein A is selected from the group consisting of an oxy group, a thio group, and a divalent saturated aliphatic hydrocarbon group, wherein at is an integer in the range of from 1 to 15 inclusive; wherein y is an integer in the range of from 1 to 15 inclusive; and wherein z is an integer selected from the group consisting of zero and one; with the provisos that (a) the sum of x-l-y-i-z cannot equal three, (b) the total number of atoms forming the cyclic ester ring does not exceed 18, (c) the total number of organic substituents attached to the carbon atoms contained in the cyclic ester ring does not exceed four, (d) from 2 to 4 continuously linked carbon atoms contained in the cyclic ester ring can represent a portion of a saturated cycloaliphatic hydrocarbon nucleus which nucleus contains from 4 to carbon atoms, and (e) the four R variables attached to any two adjacent carbon atoms contained in the cyclic ester ring can represent a portion of a fused aromatic hydrocarbon nucleus; with from about 0.001 to about 10 weight percent, based on the total weight of cyclic ester, of a group IA metal of the periodic table; under substantially anhydrous conditions; for a period of time sufficient to produce a polymer.

2. A process which comprises contacting as the sole polymerizable reagents at least two different cyclic esters which are characterized by the following formula:

(A) wherein each R, individually, is selected from the group consisting of hydrogen, alkyl, aryl, alkaryl, aralkyl, cycloalkyl, halo, haloalkyl, alkoxyalkyl, alkoxy, and aryloxy; wherein A is selected from the group consisting of an oxy group, a thio group, and a divalent saturated aliphatic hydrocarbon group; wherein x is an integer in the range of from 1 to inclusive; wherein y is an integer in the range of from 1 to 15 inclusive; and wherein z is an integer selected from the group consisting of zero and one; with the provisos that (a) the sum of x+y+z cannot equal three, (b) the total number of atoms forming the cyclic ester ring does not exceed 18, (c) the total number of organic substituents attached to the carbon atoms contained in the cyclic ester ring does not exceed four, (d) from 2 to 4 continuously linked carbon atoms contained in the cyclic ester ring can represent a portion of a saturated cycloaliphatic hydrocarbon nucleus which nucleus contains from 4 to 10 carbon atoms, and (e) the four R variables attached to any two adjacent carbon atoms contained in the cyclic ester ring can represent a portion of a fused aromatic hydrocarbon nucleus; with from about 0.001 to about 10 weight percent, based on the total weight of cyclic ester, of a group IA metal of the periodic table; under substantially anhydrous conditions; for a period of time sufiicient to produce a polymer.

3. A process which comprises contacting delta-valerolactone, as the sole polymerizable reagent, with from about 0.01 to about 3.0 weight percent, based on the weight of said delta-valerolactone, of an alkali metal; at a temperature in the range of from about 20 C. to about 225 C.; under substantially anhydrous conditions;

and for a period of time suflicient to produce a polymer.

4. The process of claim 3 whereinv said alkali metal is sodium.

5. The process of claim 3 wherein said alkali metal is potassium. V

6. A process which comprises contacting an alkyl-substituted delta-valerolactone, as the sole polymerizable reagent, with from about 0.01 to about 3.0 weight percent, based on the weight of said alkyl-substituted delta-valero lactone, of an alkali metal; at a temperature in the range of from about 20 C. to about 225 C.; under substantially anhydrous conditions; and for a period of time 'suflicient to produce a polymer.

7 The process of claim 6 wherein said alkali metal is sodium.

8. The process of claim 6 wherein said alkali metal is potassium.

9. A process which comprises contacting epsilon-caprolactone, as the sole polymerizable reagent, with from about 0.01 to about 3.0 weight percent, based on the weight of said epsilon-caprolactone, of an alkali metal; at a temperature in the range of from about 20 C. to about 225 C.; under substantially anhydrous conditions; and for a period of time sufficient to produce a polymer.

10. The process of is sodium.

11. The process of claim 9 wherein said alkali metal is potassium.

12. The process of lithium.

13. A process which comprises contacting an alkyl-su-bstituted epsilon-caprolactone, as the sole polymerizable reagent, with from about 0.01 to about 3.0 weight percent, based on the weight of said alkyl-substituted epsiloncaprolactone, of an alkali metal; at a temperature in the range of from about 20 C. to about 225 C.; under substantially anhydrous conditions; and for a period of time sufficient to produce a polymer.

14. The process of claim 13 wherein said alkali metal is sodium.

15. The process of claim 13 wherein said alkali metal is potassium.

16. A process which comprises contacting, as the sole polymerizable reagents, a monomeric lactone admixture of delta-valerolactone and alkyl-substituted delta-valerolactone, with from about 0.01 to about 3.0 weight percent, based on the total weight of the monomeric lactone feed, of an alkali metal; at a temperature in the range of from about -20 C. to about 225 C.; under substantially anhydrous conditions; and for a period of time sufficient to produce a polymer.

17. A process which comprises contacting, as the sole polymerizable reagents, a monomeric lactone admixture of delta-valerolactone and epsilon-caprolactone with from about 0.01 to about 3.0 weight percent, based on the total weight of the monomeric lactone feed, of an alkali metal; at a temperature in the range of from about 20 C. to about 225 C.; under substantially anhydrous conditions; and for a period of time sufiicient to produce a polymer.

18. A process which comprises contacting, as the sole polymerizable reagents, a monomeric lactone admixture claim 9 wherein said alkali metal claim 9 wherein said alkali metal is lactones, with from about 0.01 to about 3.0 weight percent, based on the total weight of the monomeric lactone feed, of an alkali metal; at a temperature in the range of from about 20 C. to about 225 C.; under substantially anhydrous conditions; and for a period of time sufficient to produce a polymer.

20. A process which comprises contacting, as the sole polymerizable reagents, a monomeric lactone admixture of epsilon-caprolactone and alkyl-substituted epsiloncaprolactones, with from about 0.01 to. about 3.0 weight percent, based on the total Weight of the monomeric lactone feed, of an alkali metal; at a temperature in the range of from about 20 C. to about 225 C.; under substantially anhydrous conditions; and for a period of time sufficient to produce a polymer.

21. A process which comprises contacting, as the sole polymerizable reagents, a monomeric lactone admixture of alkyl-substituted epsilon-caprolactones and alkyl-sub stituted delta-valerolactones, with from about 0.01 to about 3.0 weight percent, based on the total weight of the monomeric lactone feed, of an alkali metal; at a temperature in the range of from about 20 C. to about 225 C.; under substantially anhydrous conditions; and for a period of time sufiicient to produce a polymer.

22. A process which comprises contacting, as the sole polymerizable reagents, a monomeric lactone admixture oi different alkyl-substituted delta-valerolactones, with from about 0.01 to about 3.0 weight percent, based on the total weight of the monomeric lactone feed, of an alkali metal; at a temperature in the range of from about 20 C. to about 225 C.; under substantially anhydrous conditions; and for a period of time sufficient to produce a polymer.

23. A process which comprises contacting, as the sole polymerizable reagents, a monomeric lactone admixture of different alkyl-substituted epsilon-caprolactones, with from about 0.01 to about 3.0 weight percent, based on the total weight of the monomeric lactone feed, of an alkali metal; at a temperature in the range of from about 20 C. to about 225 C.; under substantially anhydrous conditions; and for a period of time sufilcient to produce a polymer.

References Cited in the file of this patent UNITED STATES PATENTS 2,471,023 Cook a a1 May 24, 1929 2,808,390 Caldwell Oct. 1, 1957 2,809,958 Barnes et al. on. 15, 1957 2,848,441 Reynolds et a1 Aug. 19, 1958 2,890,208 Young June 9, 1959 FOREIGN PATENTS 766,347 Great Britain Jan. 23, 1957 561,151 Canada July 29, 1958 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No 3 ,U21 ,317 February 13, I962 Eugene F. Cox et a1.

It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 1, line 43, after "metal" insert (an alkali metal) column 2, line 16, after "inclusive;" insert wherein y is an integer from I to 15 inclusive; column 4, line 34, for "disopropyl" read diisopropy l line 62, for "detla" read -delta column 6, line 34, for "polymerizating" read polymerizing column 13, lines 25 and 59, strike out "and aryloxy each occurrence, and insert instead aryloxy, a portion of an aromatic hydrocarbon nucleus which nucleus is fused to the cyclic ester ring, and a portion of a saturated cycloaliphatic hydrocarbon nucleus which nucleus contains from 4 to 10 carbon atoms and which is fused to the cyclic ester ring; column 13, lines 34 and 68, after "18,", each occurrence, insert and column 13, lines 37 and 71, beginning with "four, (d) from 2 to 4", each occurrence, strike out all to and including "aromatic hydrocarbon nucleus," in line 43, same column 13, and column 14, line 2, and insert instead four; each occurrence; column 13, lines 44 and 45, and column 14, lines 4 and 5, strike out "group IA metal of the periodic table;", each occurrence, and insert instead metal selected from the group consisting of lithium, sodium, potassium, rubidium, and cesium; column 13, line 49, and column 16, lines 5 and 14, strike out "different", each occurrence.

Signed and sealed this 7th day of August 1962.

(SEAL) Attest:

ERNEST W. SWIDER DAVID L. LADD Attesting Officer Commissioner of Patents 

1. A PROCESS WHICH COMPRISES CONTACTING AS THE SOLE POLYMERIZABLE REAGENT AT LEAST ONE CYCLIC ESTER CHARACTERIZED BY THE FOLLOWING FORMULA: 